Elastomeric film and products therefrom

ABSTRACT

Supple, microporous, breathable elastomeric films with a system of intercommunicating cells are described. The films which optionally contain inert organic or inorganic particles varying in size from about 0.02 microns to 150 microns are prepared by deposition from a solution spread on a suitable surface. Deposition is effected by exposure of the solution to a liquid which is miscible with the solvent but which does not dissolve the elastomer. The use of the film in the preparation of leather replacement compositions by integration as a grain layer in and on the surface of suitable substrates is described. For this use the selected substrate is wet with a liquid in which the elastomer is insoluble, coated with a solution of the elastomer in a solvent which is miscible with the liquid used to wet the substrate, and the wet, coated substrate is treated with additional liquid to deposit the elastomer extending into the upper strata of the substrate and above its surface.

United tates Patent [72] Inventor Wu Lan Wang Newark, NJ. [21] Appl. No.734,887 [22] Filed June 6, 1968 [45] Patented Jan. 11, 1972 [73]Assignee Tenneco Chemicals, Inc.

[54] ELASTOMERIC FILM AND PRODUCTS THEREFROM 13 Claims, No Drawings [52]11.8. C1 161/159, 117/63,117/1355,161/162,161/170,161/l90, 260/2.5 AY[51] Int. Cl B32b 5/16, B32b 5/30 [50] Field of Search l6l/83, 87, 159,160, 162, 190, DIG. 2; 260/775, 2.5 AY; 117/63,135.5

[5 6] References Cited UNITED STATES PATENTS 3,238,055 3/1966 Brightwell161/159 3,262,805 7/1966 Aoki 161/159 3,284,274 11/1966 Hulslander etal161/159 Primary Examinerwilliam J. Van Balen Attorney-Cooper, Dunham,Henninger & Clark ABSTRACT: Supple, microporous, breathable elastomericfilms with a system of intercommunicating cells are described. The filmswhich optionally contain inert organic or inorganic particles varying insize from about 0.02 microns to 150 microns are prepared by depositionfrom a solution spread on a suitable surface. Deposition is effected byexposure of the solution to a liquid which is miscible with the solventbut which does not dissolve the elastomer. The use of the film in thepreparation of leather replacement compositions by integration as agrain layer in and on the surface of suitable sub strates is described.For this use the selected substrate is wet with a liquid in which theelastomer is insoluble, coated with a solution of the elastomer in asolvent which is miscible with the liquid used to wet the substrate, andthe wet, coated substrate is treated with additional liquid to depositthe elastomer extending into the upper strata of the substrate and aboveits surface.

lELASTOMElRIC FILM AND PRODUCTS THEREFROM BACKGROUND OF INVENTION Thisinvention is concerned 'with supple, microporous, breathable elastomericfilms. It is concerned also with the use of these films for a variety ofpurposes including the preparation of novel compositions of matter whichare useful as replacements for natural leather in a wide variety ofapplications including shoe uppers. In a particularly preferred aspectof the invention fine, inert particles are dispersed throughout theelastomer.

A need has long existed in the art for a supple, breathable film havingthe physical properties to withstand hard usage in various applications.For example, the innersoles of shoes should be breathable and have goodmoisture vapor transmission in order to insure comfort to the wearer. Atthe same time, the innersole should have good tensile strength, modulusand abrasion resistance to insure long and comfortable wear. Similarproblems are encountered in sweatbands for hats, in various outerweargarments such as raincoats and gloves which must be breathable to insurecomfort. Films having such properties are also useful in gaskets,filters and analogous applications. The films may be unsupported orsupported, for example, by lamination to a woven or nonwoven fibroussubstrate, or to a resilient foam base.

Such films as have heretofore been prepared have not been completelysatisfactory in this regard. They may be breathable, or have suitablemoisture vapor transmission properties, but may fail in other respectssuch as abrasion resistance, flexibility or tensile strength. Thisinvention provides films which avoid these problems. Moreover, the filmscan be prepared to serve a variety of end uses in which there isappreciable variation in physical requirements. In other words, filmscan be prepared in accordance with this invention which accent certainproperties such as tensile strength and moisture vapor transmission; or,by slight variations in techniques, films can be prepared which accentother properties.

The films can be used alone. They can be laminated to various substrateswhich may be fibrous or nonfibrous, resilient or rigid, or may have anyof a wide variety of physical and chemical properties. They areespecially useful in the preparation of leather replacement products bydeposition in the upper strata of a leather replacement substrate insuch a manner that the film extends above the surface of the substrate.

Recently, a number of synthetic replacements for natural leather havebeen developed. While suitable in many instances as substitutes for thenatural product they have not generally attained the standards requiredto withstand the physical demands which are imposed by a variety ofshoemaking methods.

Often the substitute leather has taken the form of a polymeric coatinglaminated to fiber substrates. In shoemaking, the lasting of the leatherand its subsequent wear in the shoes subjects the leather to a varietyof three-dimensional stresses. This often results in structural failuressuch as delamination in leather replacements products. These failuresseriously limit the utility of such products. Often the stresses cause ashowthrough" problem in which irregularities of the substrate which areanalogous to the variations in density in the corium of natural leather,and responsible for many of its desirable properties, show through thepolymeric coating. This showthrough has little or no effect on thephysical properties of the product, but it does detract from itsappearance, often to the point where the product is not commerciallysuitable. Showthrough arises when irregularities in the substrate becomeapparent through the surface coating or coatings used to protect or toimprove the appearance of the substrate. They could, for example, ariseas a result of close packing of fiber bundles in some sections of thesubstrate, and could be on the surface of the substrate or in the bodythereof. In either event, when the material is stretched and compressedin the lasting operation, the irregularities show through the top of thelayer.

The problem which has been defined as showthrough" in this applicationis a well known, art recognized problem which has caused the demise ofmany materials previously proposed for use as shoe upper products. It isoften referred to as orange peel." It is caused by print through of anuneven base layer when the leather substitute is subjected to heavystretching, e.g., in the toe area during lasting.

A number of attempts have been made to solve these problems, but nonehas been completely satisfactory. Those attempts have generallyincreased the cost of the product without appreciable improvement inquality.

One approach has been to laminate a scrim layer between the substrateand the coating. This has been helpful, but not completely satisfactorysince the scrim occasionally becomes delaminated from the substrate orfrom the coating. Moreover, the scrim is usually a woven fabric whichdoes not stretch equally in all directions with the result thatadditional stresses are caused in the structure. Additionally, the scrimcauses problems in the roughing step of shoemaking and in shoe repairbecause it is so close to the surface. Very little of the surfacecoating can be removed before the outline of the scrim layer, or thelayer itself becomes apparent.

Another approach has been to apply a relatively thick polymeric coatingonto the substrate. This helps with the showthrough problem, but it alsoadds to the cost of the product. It also imparts an undesirablerubberlike characteristic to the product with the result that theproduct does not have a good leather-like" feel. The rubberlikecharacteristic of the polymer layer tends to override and mask thedesirable physical properties imparted to the total product by the fibersubstrate. The elasticity of the polymeric layer is so different fromthat of the substrate that deleterious internal stresses are introducedin the product.

In a further attempt to overcome the showthrough problem fibers havebeen dispersed in the polymeric layer. The product has been one in whichthe fibers have been dispersed so that the majority of them were free ofdirect contact with each other. This substantial discontinuity of thedispersed fibers is important since the polymeric layer is normallyquite thin, and any bunching of the fibers would manifest itself as adefect in the coating. Additionally, if there are too many fibers incontact, the polymeric coating becomes stiff and boardy, and the productloses the aesthetic qualities which are characteristic of naturalleather.

This procedure has not been entirely satisfactory. It has been foundthat if a sufficiently small amount of fiber is dispersed in thepolymeric layer to insure substantial discontinuity, the showthroughfrom the substrate is still a problem. On the other hand, if sufficientfiber is dispersed to overcome showthrough, the dispersion tends tobecome continuous with the result that the product may be lumpy anddeficient in respect of hand and break. Moreover, the fibers themselvescreate a secondary showthrough problem. The fibers are normallyappreciably less resilient than the polymer in which they are dispersed.Therefore, the fiber itself may show through under the stress ofshoemaking or wearing.

In previous procedures for the preparation of leather replacements,vapor permeable bases, especially those containing randomly distributedfibers entangled and interlocked with each other have been employed assubstrates for final products which are normally produced by laminatinga polymeric grain layer to the top surface of the substrate. Theproducts thus prepared suffer the deficiencies aforesaid.

Before describing the leather replacement products of this invention indetail it will be convenient to define certain of the terms which willbe employed.

FIBER Natural and synthetic materials of suitable denier, length andother dimensions such as polyesters, acrylics, polyamides, modacrylics,vinyls, cellulosics, wool, silk, etc. Inorganic fibers such as glass maybe used, but the preferred fibers for the preparation of leatherlikecompositions are organic fibers. They can be polyamides, such aspolyhexamethylene adipamide (nylon 66) or polycaproamide (nylon 6);polyesters, such as polyethylene terephthalate or polydimethylcyclohexylterephthalate; acrylics such as polyacrylonitrile; vinyls, such aspolyvinyl chloride or polyvinyl alcohol; cellulosics such as rayon,etc., and wool. Mixtures of two or more fiber types may be employed.

As used herein, the term "fiber includes tow, staple, continuousfilament and similar fiber forms. The fibers may be present as yarns.They may be crimped (whether or not heatset) or uncrimped. The fibersemployed will generally have a denier between about 0.5 and 6 andpreferably between 0.5 and 3. Fiber lengths of at least about 7% inchare desirable. Fibers in conventional textile lengths, e.g., up to 3 ormore inches, are generally suitable for use in this invention.

As used in describing this invention fiber" refers to a product which isat least 500 times as long as it is wide. This will distinguish fibersfrom particles which normally do not have any one dimension appreciablygreater than another dimension, and are often essentially spherical.

Fleece The structure formed by processing the fibers in the appropriateequipment including, e.g., carding, cross laying, air laying, etc. Thepreferred fleeces for use in the preparation of products of thisinvention are isotropic fleeces such as may be fonned on air-layequipment. However, a cross-laid fleece in conjunction with otherdirectional structures such as carded fleece, scrim, warp yarn, and thelike, can be used. Isotropic continuous filament structures are alsosuitable.

Foam

Relatively low density, porous, cellular, flexible, resilient materials.Polyurethane foam is preferred although rubber latex, vinyl foams andother foams having properties similar to polyurethane foams may also beused.

Web

The product formed by combining the fleece and the foam as by needlingthe fleece into the foam. Reference will also be made to composite websin which there are at least two fleece components.

Substrate The product formed by depositing an elastomer throughout theweb. Composite substrates are formed from composite webs by elastomericdeposition.

The term substrate is used herein in two different senses. [t isemployed in the generic sense to refer to any composition used inassociation with the grain layer of the invention. It is also used inthe more restricted sense of the three component fiber-foam-elastomericfiller defined in the previous paragraph. It is not believed that thiswill cause any confusion. Grain layer The term grain layer" is used inassociation with products of this invention to describe that portion ofthe total structure which is analogous to the grain layer of naturalleather. The grain layer may be prepared from the same elastomers usedto prepare the substrates or composite substrates. Because of the methodby which the grain layer is applied, it becomes integrated with thesubstrate or composite substrate with the result that the final productis not a laminate.

The foregoing rather specialized definitions are especially useful indefining the preferred leather replacement products which can beprepared in accordance with this invention. In such preferred productsthe film is deposited as a grain layer in the upper strata and above thesurface of a fibrous substrate comprising randomly oriented fibersentangled and interlocked with each other. Leather replacement products,suitable for some applications can be prepared by laminating a film ofthe invention to any of a variety of substrates including woven andnonwoven fibrous mats. The films of the invention can also be usefullyemployed in a large number of products where leather is not normallyutilized. They may, for example, be tinted and laminated to aninexpensive fabric backing to produce a product which is suitable forthe preparation of wall coverings.

THE lNVENTlON in accordance with one aspect of this invention a supple,microporous, breathable elastomeric film is provided. This film ischaracterized by a system of intercommunicating cells communicating witheach other and with both surfaces of the film. There are dispersedwithin the film from about 30 to about 120 parts by weight of inertparticles per parts by weight of dry elastomer in the size range of fromabout 0.02 microns to 150 microns. The film is preferably a polyurethaneelastomer which may contain a major or minor proportion of polyvinylchloride. Although the films are breathable, they are void free, that isthere are no holes in the elastomer which are visible even at 100xmagnification.

The supple, microporous, breathable, elastomeric film of this inventionin which the elastomer is preferably polyurethane, or a mixture thereofwith polyvinyl chloride, should be carefully distinguished from ordinaryfilled elastomeric films such as are prepared by dissolving an elastomerin a volatile solvent having a dispersed filler, coating the solution ona surface and evaporating the solvent. These films are neithermicroporous, nor breathable, nor do they have a system of cellscommunicating with each other and with the surfaces. Such films areoften made breathable by needle punching a plurality of fine holescompletely through them, but this is not a system of communicatingcells. Moreover, this treatment adversely affects physical propertiessuch as tensile strength and tear strength. It is harmful if the film isto be sewn to a base because the fine needle holes produced to make theproduct breathable reduce the resistance to propagated tears resultingfrom the sewing.

The films of this invention should also be distinguished from blown,filled elastomers which are prepared by vaporizing a blowing agentwithin the body of the elastomer, e.g., by heating. These blownelastomers, as is known, are predominantly closed cell in character.Most of the cells are individual units which do not communicate withneighboring cells.

The most useful films within the scope of this invention will range fromabout 3 to 20 mils in thickness and will contain from about 30 to aboutparts by weight ofinert filler particles per 100 parts by weight of dryelastomer. Films appreciably above or below this thickness range may beuseful for some purposes, but generally there is a decrease in thedesirable physical attributes of the products as less and less filler isused, or as the thickness of filler, especially with thin films tends todetract from the desirable suppleness of the product, and this is trueeven with relatively thick films as the amount of filler increasesappreciably above 120.

The particle size of the filler may range from about 0.02 microns tomicrons. Particles appreciably below this size range become more costlywith little compensation in physical improvements of the product. Above150 microns, the particles are generally too coarse, especially withthin films.

The preferred films from the point of view of economy and general rangeof utility are those which are from 5 to 15 mils thick and contain from50 to 80 parts by weight of inert particles in which the average size is20 to 70 microns.

The elastomeric films of this invention are prepared, in the presentlypreferred procedure, by coating a solution of the elastomer containingthe dispersed filler on a release surface, e.g., a glass or metallicsurface, and then exposing the coating to a liquid which is misciblewith the solvent of the solution, but is nonsolvent for the elastomer.This treatment results in a deposition of the elastomer as a microporousfilm in which the filler is substantially uniformly dispersed. Thedeposited film is then washed with additional liquid, if desired, anddried. After drying it can be peeled from the deposition surface, andeither used directly or stored for future use.

The filled breathable film has excellent physical properties which makeit useful for the various purposes aforesaid.

Since the most significant utility presently contemplated for the filmsof this invention is as the grain layer component of leather replacementproducts, the invention will, for con venience be described hereinafteras it is applied to the preparation of such products. In leatherreplacement products the film is deposited in such a way that it extendsinto the substrate and above its surface and for that reason is referredto as the grain layer so as to relate it to the same component innatural leather.

The leather replacement products which are a particularly preferredaspect of this invention are supple fibrous sheet compositions whichmanifest the good break, accommodation and lack of pipiness which ischaracteristic of high-quality natural leather. The grain layer whenproperly applied as described herein has good breathability, waterabsorption and water vapor transmission. While useful as a substitutefor natural leather in a wide variety of applications, they areespecially useful in the preparation of shoe uppers.

The particles used to prepare the films and other products of thisinvention may be organic or inorganic, but should be substantially inerttowards the elastomer itself or any of the components utilized inapplying the elastomer. The term inert means that the particles havelittle or no chemical effect on the elastomer itself or any of the othercomponents.

Typical of the organic and inorganic particles which may be mentioned byway of example of those which may be employed in the invention arecharcoal; aluminum dust and other metallic powders; leather dust; nylon;oxides of silica such as the dioxide; silicate compounds such as sodiumaluminum silicate and magnesium aluminum silicate; and oxides of calciumand barium, such as barytes, and talc. These products are availablecommercially in suitable particle sizes, or may be purchased and groundto suitable sizes. Microporous, microcrystalline, resilient particlesare preferred because of their ability to enhance the water absorptionand moisture vapor transmission of products prepared utilizing them.Products prepared using them also have a more uniform cell structure inthe grain layer. Microcrystalline, microporous, resilient cellulosicparticles such as may be prepared by acid hydrolysis of cellulose,followed by mechanical shearing in a water slurry and drying areespecially preferred. A typical process for the preparation of theseparticles is described in Industrial and Engineering Chemistry, vol. 54,No. 9, pages -29, Sept. 1962. In order to distinguish these particularlypreferred particles from other particles which can be employed in thepractice of this invention, they are referred to herein as microporous,microcrystalline, resilient cellulosic particles. They are availablecommercially under the name Avicel from the Food Machinery Corporation.

Microcrystalline collagens such as those which are prepared from edible,bovine collagan as water-insoluble acid salts are suitable. Similarlymicrocrystalline silicates such as the hydrated magnesium silicate whichis obtained from chrysolite asbestos in the form of colloidal,rod-shaped, submicron particles may also be employed. These products areavailable from Food Machinery Corporation under the names Avitene andAvibest, respectively.

In the finished grain layer there may be from about to about 120 partsby weight of particles per lOO parts by weight of dry elastomer. It ismost surprising to find that such large amounts of particles can beemployed without adversely affecting the product, since only relativelysmall amounts of fibers can be employed in the polymeric coatings of theprior art.

Generally speaking, leather replacement products of this invention areprepared by spreading a dispersion of the particles in a solution of theelastomer on the selected substrate, which has been previously wet withsuitable liquid. The elastomer is then deposited. The preferredprocedure for depositing the elastomer is by coagulation which iseffected by exposing the coating to a nonsolvent for the elastomer whichis at least partially miscible with the solvent of the elastomericsolution. By utilizing this procedure the elastomer is deposited as astable, microporous product characterized by a system ofintercommunicating cells. The elastomer-containing particles aredeposited within the upper strata of the substrate, below the topsurface, and also extend above the surface.

The thickness of the finished grain layer above the substrate willtypically be from about 5 to 30 percent of the total thickness of thegrain layer plus the substrate. Normally, this will be from about 5 to20 mils, and again the thickness may be controlled by the manner ofdeposition or by utilization of several layers, some of which may beparticle free. In any event, the total thickness of the final product isnormally from about 20 to I00 mils.

There are a number of additional features of this invention which permitthe production of products with greatly increased physical and aestheticvalues compared with previously known leather substitutes. For example,after the first elastomer has been coagulated as described above, theprocess can be repeated any desired number of times to produce grainlayers of varying thicknesses. The physical and chemical characteristicsof the selected elastomer used in each instance can be varied so as toproduce a product having a gradient density within the grain layer suchthat the density increases progressively towards the surface.

If desired, the last layer can be sprayed on to the previouslycoagulated layers and the solvent permitted to evaporate. The result isthat a thin deposit of elastomer forms on the underlying layers andhelps to seal the surface so as to inhibit liquid penetration.

In one method of practicing this invention the substrate is lightlybuffed before coagulating the initial grain layer. This tends to raise anap on the surface of the substrate, and the raised nap becomes bondedin the elastomer of the grain. This contributes to the strength of thefinal product. A sufficient amount of elastomer is normally deposited inand on the substrate to submerge all of the raised nap in the grainlayer.

In a particularly preferred aspect of this invention, the elastomersolution is spread as a coating on a flexible release surface which maybe a specially treated paper or a plastic film such as polyethylene orpolypropylene. The substrate, wet with the deposition liquid is thenbrought into surface contact with the wet elastomer solution layer andthe package passed through the nip of combining rolls. The majorproportion of the elastomer is thus deposited within the upper strata ofthe substrate. Additional elastomer may be deposited by the proceduresdescribed above, if desired.

While this invention has been described principally as one in which onlyone surface of a substrate has been treated, it will be appreciated thatthe invention may also be practiced by treating both surfaces. Theproduct thus produced can be used as prepared, or it may be splitlongitudinally to form substantially identical products.

The elastomers utilized in the practice of this invention may beselected from a relatively large number of products which arecommercially available or can be prepared by known methods. The selectedelastomer will be tough, flexible, abrasion resistant, not subject tocold flow, solvent resistant and capable of deposition as a microporousbreathable layer with moisture vapor transmission properties similar tothose of natural leather. In the microporous film the cells will be verysmall, generally of an order such that they are not visible even at xmagnification. They will form an intercommunicating system in which alarge proportion of the cells open on one or more of their neighbors.The cells communicate witheach other and with both surfaces. This doesnot preclude the possibility that the deposited elastomer will containsome closed cells.

A convenient test for the initial evaluation of potential elastomers asfilms or grain layers is to deposit the elastomer from a solution by theaddition of an immiscible nonsolvent. If the elastomer deposits as afilm, this is an indication that the elastomer is in the correctmolecular weight range. The film should dry to a substantially uniformlyopaque microporous layer which retains its opacity indefinitely. Thedevelopment of transparency indicates that the micropores of the filmhave collapsed demonstrating that the molecular structure is notsufficiently rigid to produce a satisfactory film.

If the dry opaque film appears to be of adequate rigidity, it is nexttested for moisture vapor transmission.

Moisture vapor transmission can be tested by placing 10 ml. of water ina flanged cup known as the Payne Permeability Cup. The film is placedover the cup and held in place by clamping it between a circular ringand the flange of the cup. The loaded cup is then placed in a dessicatorover the anhydrous calcium chloride at substantially constant ambienttemperature. The cup is reweighed at the end of 24 hours to determinethe weight of water which has permeated through the test film and isthus lost from the cup. This value is recorded as the moisture vaportransmission. The test is a standard test known as the PaynePermeability Test. Elastomers suitable for use in this invention willproduce a 10- mil thick particle-free film having a density of fromabout to 60 pounds per cubic foot and a moisture vapor transmission offrom about 100 to 200 mg./cm. /24 hours.

The same test may be employed to determine the moisture vaportransmission properties of leather replacement products. It should benoted, however, that the values obtained will vary somewhat depending onwhether the grain layer on the opposite side of the product faces thewater.

The preferred polymers for use in the invention are polyurethanes. Theseare a well known class of elastomers obtained by reaction betweenorganic polyisocyanates and an active hydrogen containing material suchas polyethers and polyesters with a plurality of hydroxyl groups on thepolymer chain. Dihydroxy compounds are preferred. The reaction iscarried out by reacting the hydroxyl terminated compound with a molarexcess of organic isocyanate to produce an isocyanate terminatedprepolymer. The prepolymer is then reacted with a chain extendingcompound such as water, active hydrogen containing amino compounds,amino alcohols, or diols such as n-butane-diol, ethylene glycol,propylene glycol, and the like.

Suitable chain extenders include water, hydrazine, N- methyl-bis aminopropylamine, dimethyl piperazine, 4- methyl-m-phenylene diamine,diaminopiperazine, ethylene diamine. Mixtures of chain extending agentscan also be employed.

The prepolymer can be prepared by first mixing a molar excess of thepolyisocyanate with the active hydrogen containing polymeric materialand heating the mixture at about 50l 20 C. Or, the polyisocyanate can bereacted with a molar excess of the active hydrogen containing polymericmaterial, and the reaction product capped by reacting it with moreisocyanate.

Aromatic, aliphatic and cycloaliphatic isocyanates or mixtures thereofcan be used in forming the prepolymer. These include, e.g.,tolylene-2,4-diisocyanate; tolylene-2,6-diisocyanate; m-phenylenediisocyanate; biphenylene 4,4-diisocyanate; methylene bis-(4-phenylisocyanate); 4-chloro-1,3- phenylene diisocyanate;naphthalene-l,S-diisocyanate; tetramethylenel ,4-diisocyanate;hexamethylenel ,6-diisocyanatc; decamethylene-l l O-diisocyanate;cyclohexylene- 1,4-diisocyanate; methylene bis(4-cyc|ohexyl isocyanate)and tetrahydronaphthalene diisocyanate. Arylene diisocyanates, that isisocyanates in which the isocyanate groups are attached to an aromaticring, are preferred. In general, they react more readily than doalkylene diisocyanates.

Polyalkylene ether and ester glycols are preferred activehydrogen-containing polymeric materials for the prepolymer formation forreasons of availability and economy. The most useful polyether glycolshave a molecular weight of 300 to 5,000, preferably 400 to 2,000, andinclude for example,

polyethyleneether glycol, polypropylene ether glycol,polytetramethyleneether glycol, polyhexamethylene-ether glycol,polyoctamethyleneether glycol,

polynonamethyleneether glycol, polydecamethyleneether glycol,polydodecamethyleneether glycol, and mixtures thereof. Polyglycolscontaining several different radicals in the molecular chain such as,for example, the compound HO(CH OC C4O),, wherein n is an integergreater than 1 can alsobe used.

Polyester glycols which can be used in conjunction with the polyalkyleneether glycols may be produced by reacting acids, esters or acid halideswith glycols. Suitable glycols are polymethylene glycols, such asethylene-, propylene-, tetramethylene-, decamethylene glycols,substituted polymethylene glycols such as 2,2-dimethyl-l,3-propanediol,cyclic glycols such as cyclohexanediol and aromatic glycols such asxylylene glycol. Aliphatic glycols are generally preferred when maximumproduct flexibility is desired. These glycols are reacted withaliphatic, cycloaliphatic or aromatic dicarboxylic acids or lower alkylesters or ester forming derivatives thereof to produce relativelylow-molecular weight polymers, preferably having a melting point of lessthan about 70 C., and molecular weights like those indicated for thepolyalkyleneether glycols. Acids suitable for preparing such polyestersare, for example, succinic, adipic, suberic, sebacic, terephthalic andhexahydroterephthalic acids and the alkyl and halogen substitutedderivatives of these acids.

The chain extension reaction may be carried out at a temperature up toabout C., but is usually effected at about room temperature, i.e., 25 to35 C. During the reaction, prepolymer molecules are joined together intoa substantially linear polyurethane polymer, the molecular weight ofwhich is usually at least 5,000 and sometimes as high as 300,000. Thereaction can be carried out without a solvent in heavy duty mixingequipment or it can be carried out in a homogeneous solution.

Since the resulting polyurethane polymer has rubberlike elasticity, itis referred to as elastomer," although the degree of elasticity andrubberlike resilience may vary widely from product to product dependingon the chemical structure of the polymer and the materials incombination with it.

Polyvinyl chloride may be used in conjunction with the polyurethanedescribed above. When making a flexible shoe upper material or the likefrom a blend of polyurethane elastomer and polyvinyl chloride polymer,it is often preferred to employ a major proportion (over 50 weightpercent) of the former and a minor proportion (less than 50 weightpercent) of the latter. However, useful films are also obtainable inaccordance with this invention when the elastomer blend contains a majorproportion (at least 51 percent by weight) of polyvinyl chloride.

Various additives such as stabilizers, coloring agents, plasticizers,and the like, can be added to the elastomer solution to enhance theproperties or appearance of the final product.

The preferred solvent for the preparation of the elastomer solution isdimethyl formamide because of its high-solvent power and becauseit ismiscible with water, which is the preferred depositing or coagulatingliquid. However, other solvents and solvent blends can also be employed.Dimethyl formamide and methyl ethyl ketone in various proportions fromuseful solvents for use in association with water. The criteria forselecting the solvent or solvent blend are that they should dissolve theelastomer and be at least partially miscible with another liquid whichdoes not dissolve the elastomer.

The preferred nonsolvent liquid is water because it is the leastexpensive. Other nonsolvent liquids, including aqueous blends such aswater and alcohol, may be employed. It is preferred therefore that theelastomer solvent be miscible with water or aqueous blends.

A feature of this invention is the discovery of methods for depositionof the elastomer in a manner such that a microporous film is formed inand on the substrate in which the micropores communicate with each otherand with the surface. In all of these newly discovered procedures thesubstrate is first wet with a liquid which is nonsolvent for theelastomer and miscible with the solvent of the elastomeric solution.Excess liquid is then removed, as by squeezing. Sufficient liquid shouldbe removed so that the substrate, although wet, is substantially free ofany surface film of liquid. This aids in permitting the elastomer topenetrate into the upper strata of the substrate. The elastomericsolution is then applied to the surface of the wet substrate by anysuitable technique such as curtain coating, spraying, roller-coating,knife coating, and the like. The elastomer is then deposited by exposingthe solution to a miscible nonsolvent in either the liquid or vaporform. For example, the coated substrate can be dipped into a water bathand held in the bath until substantially all of the elastomer hasdeposited, or the coated substrate may be exposed to a humid atmosphereto deposit the elastomer. In either event, the product is then washedand dried. It may be advantageous in certain instances to add sufficientwater or other miscible liquid to the elastomeric solution to bring theelastomer to the point of incipient precipitation before coating thesubstrate and finally depositing the solid elastomer. It is a particularadvantage of the microporous, microcrystalline, cellulosic particleswhich are preferred for use in this invention that elastomers can bedeposited as void-free films from solution dispersions containing themwithout the use of incipient precipitation methods. The uniformity ofthe grain layer may often be improved by wetting the substrate with aliquid mixture containing up to about 40 percent of the same solventused in the elastomeric solution together with the miscible nonsolvent.it is understood, of course, that other liquids or liquid blends as wellas vapors of the liquids or blends may be used in the same manner as thewater.

For thin films of deposited elastomer the preferred procedure is tospray a light film of the elastomer solution containing the dispersedparticles onto the wet substrate, and to deposit the elastomer byexposing the treated product to a humid atmosphere or to a liquidnonsolvent. For heavy films it is preferred to cast a heavy covering ofthe solution dispersion on the surface of the wet substrate prior todeposition of the elastomer. The spray technique may be used if thethickness of dry elastomer above the surface of the substrate is to beless than mils. Casting is preferred if the thickness is more than 10mils. An especially preferred combining technique which may be used witheither thin or thick layers is described above.

The presently preferred process for attaining the advantages of thisinvention will now be described in more detail. The process is designedto produce a grain layer which is integral with the upper strata of thesubstrate. Broadly speaking, the process comprises the steps of:

1. Wet the substrate with a liquid which is miscible with the solventused to dissolve the selected elastomer or mixture of elastomers, but inwhich the elastomer is not appreciably soluble. Wetting can beaccomplished by soaking the substrate in the selected liquid andsqueezing to remove the excess. Care should be taken to be certain thatat least the upper strata of the substrate is saturated with the liquid,but that there is substantially no surface film of liquid. A surfacefilm of liquid inhibits penetration of the elastomer causing it todeposit as a surface coat which is not integral with the substrate.

2. Coat the surface of the wetted substrate with a solution of theelastomer or elastomer mixture. For thin coats of deposited elastomerthe preferred procedure is to spray a light film of the solution ontothe substrate, and to coagulate by exposing the treated product to ahumid atmosphere or to wash with water. For heavy films it is preferredto cast a heavy covering of the elastomer solution on the surface of thesubstrate prior to water washing or exposure to a humid atmosphere. Thespray technique will normally be used if the thickness of the dryelastomer above the surface of the substrate is to be less than 10 mils.Casting is preferred if the thickness is more than 10 mils. Not all ofthe elastomer solutions need to contain the particulate filler. In fact,useful products can be obtained, as is illustrated in the examples, ifno filler at all is employed. The term coat" as used herein alsoincludes the especially preferred process described above in which theelastomer is deposited from a release surface.

3. Expose the coated, wetted substrate to the miscible liquid. This maybe accomplished as suggested above, by again dipping the product in themiscible liquid or by exposing it to vapors of the liquid. This causesthe elastomer to deposit as a microporous layer with a system of cellscommunicating with ill each other and with the surface. The exactprocedure and conditions employed in this step depend upon whether ornot additional elastomer is to be deposited. If only one layer ofelastomer is to be utilized as the grain layer, it is best to wash outsubstantially all of the solvent. lf several layers are to be used, itis best to leave some of the solvent in the substrate, since thispermits subsequent elastomeric solutions to penetrate the lower layers.The elastomer from the second and subsequent layers thereby becomesintegral at least with the layer immediately below it. Of course, ifseveral layers are employed, substantially all of the solvent is washedout of the last layer.

4. If the first or any subsequent layer is to be coated with anadditional layer the product is again squeezed so that there is nosurface film of miscible liquid or of miscible liquid mixed withsolvent. The process is then repeated.

The product may then be dried, either by standing at ambienttemperature, or in a heated atmosphere, or by forced, hot gas.

it is preferred in the practice of this invention to deposit a pluralityof microporous layers of elastomer. This helps mask showthrough, andproduces a product which is more satisfactory in respect of break,accommodation, hand, appearance, feel and other aesthetic properties ofleather than are products with only one relatively thick grain layer.

Additionally, the use of several thin elastomeric layers allows for theproduction of a final product in which there is a gradient densitywithin the grain layer. It has been found that the lower the rate atwhich the elastomer is permitted to deposit or coagulate, the more densewill be the microporous deposit. Under the same conditions of exposureto the coagulating liquid, higher molecular weight elastomers willdeposit more rapidly than will the lower molecular weight products. Byutilizing these findings the density of the grain layer can be varied asit is formed.

The solutions of elastomers containing dispersed particles which aredescribed herein are useful for the production of grain layers on anumber of substrates which are employed in the preparation of leathersubstitutes and for other purposes. These solutions contain dissolvedelastomer together with from about 30 to 120 parts by weight ofparticles based on the dry elastomer content. The concentration ofelastomer in solution may vary within a wide range and will be selectedat least partly on the basis of the method selected for coating thesubstrate. Thus, solutions which can be knife coated or roller coatedonto the substrate might be too viscous for use with sprayingtechniques. Solutions which are too dilute may be wasteful of solventeven if solvent recovery techniques are employed. Moreover, they willrequire extra large equipment. Optimum concentrations will also dependupon the elastomer or elastomer mixture chosen. The concentration of theelastomer in solution is generally sufficient if held within the rangefrom about 2 to l5 percent for spraying. For casting it is preferred toutilize solutions in which the elastomer concentration is about 15 to 45percent. Excellent results in respect of economy, masking ofshowthrough, break, hand, lack of pipiness and other leatherlikecharacteristics are obtained with such solutions when they contain from50 to parts by weight of inert particles for each parts by weight ofelastomer.

A suitable substrate for use with the grain layers of this invention isdescribed and claimed in copending application Ser. No. 562,532, filedJuly 5, 1966, now abandoned, the teachings of which are incorporatedherein by reference.

This application describes and claims breathable, supple fibrous sheetcompositions comprising an interlocking network of fibers and a cellularmaterial such as polyurethane foam in which there are void spacesbetween the fibers and the foam. These void spaces are substantiallyfilled with a soft, resilient filler material which may be the sameelastomer which is utilized in this invention but is not necessarily so.

The substrate may be prepared by placing a fleece of fibers on a sheetof polyurethane foam and forcing the fibers into the ill foam,preferably be needling. The resulting web is then compressed at elevatedtemperatures and pressure and impregnated with an elastomeric solutionsuch as is described above. The elastomer is then deposited in the webusing substantially the same procedures as are used to deposit theelastomer of this invention. The product thus formed is again compressedto form a substrate which may be utilized as a base for the grain layerof this invention.

The flexible, cellular polyurethane foam used in the preparation of theabove described substrate is a well known class of polymers the mostfamiliar members of which are prepared by reacting polyhydroxyterminated polyethers or polyesters with organic polyisocyanates such as2,4- and 2,6- tolylene diisocyanates in the presence of a gas-producingagent such as water or liquid halogenated hydrocarbons, particularlyfluorohydrocarbons such as those available under the trademark Freon.

Polyurethane foams which can be employed are those requiring acompression of about 3 to 100 pounds per 50 square inches to produce a25 percent deflection on a two inch sample at 25 C., in accordance withASTM test number 1564-59T for indent load deflection. Preferably theywill have a tensile strength of about 5 to 35 pounds per square inch, anultimate elongation between about 100 and 400 percent, and a tearstrength of about 0.6 to 5 pounds per inch. The preferred foams are opencell with about 25 to 100 cells per linear inch and a density of about0.8 to 6 pounds per cubic foot.

The fiber foam combination, or web, is preferably prepared by needlingthe fibers of the fleece into the foam sheet, which may be from about0.020 to 1.5 inches thick. The fibers are needled into the foam at apenetration density of from about 250 to i500 penetrations per squareinch. The web may then be turned over and needled from the other side ata penetration density of about 200 to 1,500 penetrations per squareinch. A third needling from the fleece side at roughly the samepenetration density may be employed.

The degree of penetration of the needling will vary with the thicknessof the sheet. Sufficient penetration will be achieved if at least 50percent of the penetrating fibers penetrate at least about 75 percent ofthe sheet thickness and at least some of the fibers completely penetratethe sheet. It is preferred that at least 10 percent of the fiberscompletely penetrate the sheet. Convention needling devices, preferablyfitted with relatively fine needles having a number of barbs which snagthe fibers and force them through the foam.

The fleece may be made of any of the common natural or synthetic fibersor fiber blends defined above, desirably with fiber lengths of at least'72 inch. Nonwoven fleeces of comparatively loose construction arefavored. These include, for example, loosely knit yarn structures, websproduced by carding, air-laying, and the like. The fleece may have aweight between 2 and 24 ounces per square yard. The presently preferredfleeces are air-laid nonwoven fleeces having a weight of from about 3 to10 ounces per square yard. Two or more superimposed fleeces may be used.

The web produced by needling the fleece into the foam is next compressedat elevated temperature and pressure. The selected temperatures andpressures are such that neither the fiber or the polyurethane flows, sothat fiber is not deformed and the cellular structure of thepolyurethane foam is not lost. The temperature is usually from about 230to 375 F., and in flat bed presses the pressure is from about 100 to 400pounds per square inch. The compression time in flat presses is fromabout 30 seconds to minutes. Where other equipment is used, the time ofcompression will be varied to produce equivalent compression conditions.For example, equivalent compression times for a rotary press aregenerally found to be somewhat lower than with a flat-bed press.

The web obtained after compression is a supple, integrated fiber foamcombination which contains a large number of void spaces in which thefibers are held apart by the foam. The composition of the web depends,of course, on the thickness,

density and other characteristics of the fleece and the foam. Typicallythe web may comprise ID to percent by weight fibers and 20 to percentfoam, based on the total weight. It may vary from about 20 to I00 milsin thickness, and from about 15 to pounds per cubic foot in density.Webs appreciably above and below these ranges may also be produced andusefully employed in the practice of this invention.

The void in the web are next substantially, although not completely,filled by depositing an elastomer which may be of the same class, andmay be selected using the same techniques as the elastomers describedabove. Deposition may be effected using the same procedures as describedabove. The preferred procedure is to impregnate the web with a solutionof the elastomer and to soak the wet, impregnated web in water oranother aqueous medium. An alternate procedure for depositing theelastomer is to evaporate the solvent. The evaporating or bakingtemperature employed should be high enough to evaporate the solvent, butnot high enough to evaporate the solvent, but not high enough to causethe elastomer to flow. The amount of solution originally impregnatedinto the web is such that the dry elastomer added is from about 25 to 75percent by weight, based on the total weight of the substrate. The fibercontent of the substrate may vary from about 5 to 55 percent by weight,and the foam content from about 10 to 60 percent by weight; allpercentages being based on the total weight of the composition.

The water wash technique for depositing the elastomer produces a productwhich is somewhat more breathable than that produced by evaporating thesolvent. The fact that the product is breathable no matter whichtechnique is employed clearly establishes that the void spaces whichwere present in the web are not completely filled in the substrate.Substrates produced by the water wash technique generally have betteraesthetic properties, such as hand, break, accommodation, etc., and thisprocedure is preferred when these qualities are important in the end useof the product.

In the last step, the substrate is again compressed under conditionssuch that the surface is smoothed and the substrate is permanently set.As used herein the term permanently set" means that the substrate willnot return to its original volume when the heat and pressure areremoved, but will substantially retain the volume which it assumed whensubjected to these influences.

The processing conditions which are applied in the same manner asdescribed above in connection with the initial compression step are:time, about 5 seconds to 3 minutes; temperature, about 65 to 250 F.;pressure, about 50 to 300 pounds per square inch.

The product thus produced is similar in structure to natural leather,which has an interlocking system of fiber or fiber bundles runningthrough its entire thickness. The fibers are held apart by a relativelysoft, resilient fatty substance which does not prevent their restrictedmovement within the body of the structure. As in natural leather thefibers retain their flexibility, and because they are able to move inthe soft filler material they are able to adjust themselves to react tothe stresses which are applied, for example, in the lasting of theleather or the wearing of the shoe so as to disperse the stress overseveral fibers.

When this substrate is coated in accordance with this invention usingthe procedure described above the resulting product is a breathable,supple, fibrous sheet composition comprising an interlocking network offibers and foam having void spaces therebetween in which the fibers arecapable of restricted movement, the network having dispersed therein asoft, resilient filler which substantially, but not completely fills thevoid spaces; the said composition being integral with a microporouselastomeric film having from about 30 to I20 parts by weight ofparticles per 100 parts by weight of elastomer dispersed therein. Atleast part of the film is deposited within the upper strata of thecomposition while a part of it extends above the surface thereof.

The web described above may also be used in association with the grainlayer of this invention. The web is more fully described in commonlyassigned, copending Pat. application Ser. No. 487,301, filed Sept. 14,1965, now US. Pat. No. 3,477,898, the teachings of which areincorporated herein by reference.

The preferred substrate for use with the grain layers of this inventionare those described in commonly assigned, copending Pat. applicationSer. No. 719,219, filed Apr. 5, 1968, now abandoned the teachings ofwhich are incorporated herein by reference.

This application describes and claims a substrate which is animprovement over the substrate described and claimed in theabove-identified application, Ser. No. 562,532. The most importantimprovement is that a composite substrate is produced having a gradientdensity such that the flesh side is less dense than the grain side withthe result that the flesh side is relatively more compressible than thegrain side. This is an important development. The product very closelyreproduces the gradient density found in natural leather. As aconsequence it is more capable of withstanding the rigors of shoemaking,especially the tendency towards surface distortions in areas ofexceptional stress such as in the toe and heel areas of the shoe.

The substrates are produced from composite webs in which webs such asthose described above serve as base webs. A fleece of fibers ismechanically bonded, as by needling, to the base web. The fibers in thesecond fleece are no coarser than, and preferably less coarse than thefibers in the base web. The composite web thus produced is compressed,and the elastomer is deposited in the void spaces of the base web andthe interstices of the superimposed fleece using the same techniquesdescribed above. The elastomer is selected using the same criteriapreviously outlined. The product thus produced may be further heattreated under pressure although it is not essential to do so.

The foams, fibers, elastomers, solvents and nonsolvents utilized in thepreparation of these composite substrates may be the same as are used inthe preparation of the substrates of Ser. No. 562,532. The proceduresfor needling and depositing the elastomer are also similar. Thecompression steps, however, are less rigorous. They are, in the firstcompression, from about 250 to 375 F. ata pressure of from about to 100pounds per square inch for a period of from about 20 seconds to 5minutes. The conditions of the heat treatment are the same as in thecompression step unless a plurality of fibers is employed in the topfleece at least one of which is thermoplastic. In that event, the heattreatment may be effected at a temperature of from about 300 to 350 F.,at a pressure of from about 2 to 5 pounds per square inch for from aboutto 30 seconds.

In the preferred embodiment of the invention, the top fleece of thecomposite substrate is prepared from a plurality of fibers at least oneof which is thermoplastic under the conditions at which the initialcompression step is carried out. it is most convenient to use a fiberpair. The thermoplastic fiber flows slightly with the result that itbecomes bonded to the other fibers at spaced-apart points. This has theeffect of increasing the dimensional stability and modulus of thecomposite substrate without adversely affecting its other properties. Ifa thermoplastic fiber is used, the amount will normally vary from aboutto 50 percent, based on the total weight of fiber in the top fleece.

The product produced by the process described is a supple, fibrous sheetcomposition characterized by a gradient density such that the densitydecreases from the top to the bottom comprising:

a. a base web which is an interlocking network of randomly oriented anddistributed fibers in a polyurethane foam with void spaces therebetween,

b. a top fleece mechanically bonded to the surface of said base web andcomprising additional fibers, the denier of which is no greater than thedenier of said randomly oriented fibers, said additional fibers havingfine interstices therebetween, and being predominantly in a horizontalplane, and

c. a soft, resilient, elastomeric filler which substantially, but

not completely fill said void spaces and said interstices.

In the composite substrate the dry elastomer content varies from about25 to 75 percent, the fiber content from about 5 to 55 percent, and thefoam content from about 10 to 25 percent, all based on the total weight.The weight of the top fleece varies from about 10 to 25 percent, basedon the total weight of the composite substrate.

Other suitable substrates are known and can be formed with the grainlayers of this invention to produce products which are suitable asleather replacements for a variety of end uses. These are described, forexample, in US. Pat. Nos. 2,910,763; 2,978,785; 2,723,935; 3,067,483;3,238,055 and 3,000,757.

The following examples are given by way of illustration only and shouldnot be considered as limitations of this invention, many apparentvariations of which are possible without departing from the spirit orscope thereof. The examples specifically illustrate many of the fibers,foams, particles and elastomers which can be used in the practice ofthis invention. Other components of products within the scope of theinvention can be readily selected by following the teachings of theforegoing disclosure.

EXAMPLE 1 Fibers OF percent 1.5 denier by 1.5-inch nylon 66 are air-laidon a webbing machine to produce a fleece of 3 oz./sq. yard. This fleeceis integrated with a 0.025-inch-thick sheet of polyester polyurethanefoam having a density of approximately 1.5 lb./cubic foot, as follows:

a. 600 penetrations per square inch from the fiber side (300penetrations at 11 16-inch depth, 300 penetrations at 9/ 16- inchdepth).

b. 600 penetrations per square inch from the foam side (300 penetrationsat 9% inch, 300 penetrations at 7/16 -inch depth).

The web with the fiber side up is then brought into contact with a newlylaid fleece of a 2:1 blend of 1.5 denier by 1.5-inch nylon 66 and 1.5denier by 1.5-inch polyester fiber. It is again cast through a needleloom with the fiber side up to produce a composite web. The penetrationdensity is 600 penetrations per inch at 9/32-inch depth.

The resulting composite web is compressed in a rotary press during adwell time of 1 minute at a belt pressure of 5 lbs/sq. inch whileapplying heat to the fiber side at 315 F. to cause the ester fiber tobond to the nylon fiber at spaced-apart points.

The composite web is then impregnated with a polyester polyurethaneelastomer solution in dimethyl formamide having a 20 percent solidsconcentration, and passed through metering rolls so that the total wetadd on is 500 percent. The elastomer is the reaction product ofdiethylene glycol, adipic acid and toluene diisocyanate (Helastic 1360).The impregnated web is next passed into a water bath so as to depositthe elastomer in the composite web. The water bath is equipped withrollers to move the product along. The product is washed with water bypassing it through a second water bath similarly equipped with rollersand finally dried.

The dried substrate thus produced is immersed in an aqueous bath. Thewetted product is squeezed through rollers to produce a wet substratehaving no surface film of liquid. A solution containing 10 percent byweight of a polyester polyurethane elastomer in dimethyl formamide isthen spray-coated onto the surface to produce a film approximately2-mils thick. The coated substrate is then passed through an aqueousbath to deposit the elastomer as a microporous surface coating whichextends into the upper strata of the substrate. The product is washedwith water, dried and spray coated with an acrylic decorative finish.

The resulting product is useful as a replacement for natural leather.

By alternately wetting the substrate with the same liquid mixture,squeezing to produce a surface film-free product, spray coating anddepositing the elastomer as described above, the degree to which themicroporous grain layer extends above the surface is increased. Theproducts produced are not laminar. The elastomer from each successivetreatment becomes integrated with the elastomer of the previoustreatment so that in the final product the grain layer extends into theupper strata of the substrate and above its surface.

The elastomer solution utilized in the preparation of the grain layer isprepared by reacting 74 parts by weight of polyethylene glycol adipatehaving a molecular weight of about 2,000, terminal hydroxyl groups andan hydroxyl content of 1.5 percent at ll C. for 1 hour with 19.75 partsby weight of p,p-methylenediphenyl diisocyanate in drydimethyl-formamide and chain extending by reaction at 35 C. for 1 hourwith 7.1 parts by weight of methylene dianiline as a 30 percent solutionin dimethyl formamide. The solution which contains percent by weight ofthe elastomer is diluted with additional solvent to produce a solutionhaving a 10 percent solids content. The elastomer deposits a stable filmwhen tested in accordance with the procedure described above.

EXAMPLE 2 EXAMPLE 3 Fibers of 100 percent 1.5 denier by 1.5-inch nylon66 are air-laid to produce a fleece of 8.5 oz./sq. yard. This fleece isgrain layer exposing the elastomer-coated substrate to a humidatmosphere in which the relative humidity is about 90 percent at roomtemperature.

EXAMPLE 4 The suitability of a number of fillers for use in the productsof this invention is established by casting elastomeric films of thepolyester polyurethane elastomer of example i on a smooth glass surface.

The selected particulate samples of the fillers are taken up in anelastomeric solution in dimethyl formamide containing about 25 percentelastomer by weight and the viscosity adjusted by the addition ofdimethyl formamide to produce a solution dispersion which would not flowoff the glass surface before formation of the elastomeric film. Thetotal dry solids content of the solution dispersions varies from about25 to 30 percent.

The films are prepared by coating a smooth glass surface with a layer ofthe solution dispersion which is about 35 mils in thickness. The glassis then immersed in a bath containing 70 parts dimethyl formamide and 30parts water to deposit the elastomeric film. The deposited film isfinally washed in water and dried. The films are opaque and retain theiropacity indefinitely. The films are then peeled from the glass and theirproperties tested by standard procedures. The results are listed intable 1.

These particle filled films are useful alone as sweatbands for hats.They were laminated to a sheet of urethane foam using a copolymer of2-ethyl hexyl acrylate and vinyl acetate and die cut to form inner solesfor shoes. They were laminated to a cotton backing and the resultingproduct formed into gloves which were especially suitable as work glovesbecause of their abrasion resistance and breathability.

Modulus in Elon atlon p.s.i. at- Ultimate Thickness, MEDS 1 at M DS,Ultimate elongation Density, Filler Quantity 1 mils p.s. percent 25%100% T8 in p.s.i. percent lb./l't. MVP

No filler 0 0. 5 95 35 70 210 743 465 20. 8 159. 00 Aviool 4 71. 4 11198 11 320 415 807 378 52.0 104. 00 Leather dust 42. 8 10 226 10 450 950l, 210 180 4& 8 51. 26 Molecular sieve 71. 4 10 95 35 69 188 425 293 60.8 159. 82 Cab-O-Sil 6 38. 0 9 165 10 207 332 555 215 52. 4 104. 80

1 Amount of filler per 100 parts of elastomer. 2 Maximum ElasticDeformation in pounds per square inch. 3 Moisture Vapor Transmission inmg./cm. /24 hours.

4 Microporuos, microcrystalline, resilient cellulosic particles,particle size 1-100 microns, average 38 microns.

Hydrated crystalline sodium aluminum silicate, particle size 0.01-0.05mi Colloidal silica, particle size 0.012 micron. integrated as describedin example 1 into a 0.025 inch thick sheet of a polyester polyurethanefoam having a density of 1.5 lbs/cubic foot. The resulting web iscompressed in a flat press during a dwell time of 3 minutes, at apressure of 300 lbs./sq. inch and a temperature of 300 F. The compressedweb is then impregnated with a solution of the same polyesterpolyurethane elastomer used in example 1 in dimethyl formamide with asolids content of 35 percent. The elastomer is deposited in the webusing the same procedure as in example 1. The product is washed, driedand heat treated in a flat press at 275 F. and 75 lbs/sq. inch pressurefor 3 minutes.

The dried substrate is immersed in a water bath and squeezed to removesufficient water so that there is no surface film. it is coated with asolution containing 30 percent by weight of the same polyesterpolyurethane elastomer employed in example 1 in dimethyl formamide. Thedepth of the wet film thus produced is approximately 40 mils. Theproduct is passed into a water bath to deposit the elastomer as a grainlayer. it is then washed with water and dried.

The procedure is repeated except that no elastomeric filler is depositedin the fiber-foam web and the heat treatment is omitted.

The products produced are useful as replacements for natural leather.

Similar products are produced by repeating the procedures of thisexample except that the elastomer is deposited as a CIOH.

These results establish that the elastomer solutions and the solutiondispersions are well suited for the preparation of the products of thisinvention. it will be noted that by selection of the particular fillerthe physical properties of the film can be varied within wide limits. insimilar experiments it was shown to be possible to control the physicalproperties of the filled film by varying the amounts of filler from 30to 120 parts by weight per parts of dry elastomer.

EXAMPLE 5 Fibers of 100 percent 1.5 denier by 1.5-inch nylon are airlaidon a webbing machine to produce a fleece of 3 oz./sq. yard. This fleeceis integrated with a 0.025 -inch-thick sheet of polyester polyurethanefoam having a density of approximately 1.5 lb./cubic foot, as follows:

a. 600 penetrations per square inch from the fiber side (300penetrations at 11 16-inch depth, 300 penetrations at 9/16- inch depth),

b. 600 penetrations per square inch from the foam side (300 penetrationsat 9% inch, 300 penetrations at 7/ l 6-inch depth).

The web with the fiber side up is then brought into contact with a newlylaid fleece ofa 2:1 blend of 1.5 denier by 1.5-inch nylon 66 and 1.5denier by 1.5 inch polyester fiber. it is again east through a needleloom with the fiber side up to produce a composite web. The penetrationdensity is 600 penetrations per inch at 9/32-inch depth.

The resulting composite web is compressed in a rotary press during adwell time of 1 minute at a belt pressure of lbs/sq. inch while applyingheat to the fiber side at 315 F. to cause the ester fiber to bond to thenylon fiber at spaced-apart points.

The composite web is then impregnated with a polyester polyurethaneelastomer solution in dimethyl formamide having a 20 percent solidsconcentration, and passed through metering rolls so that the total wetadd on is 500 percent. The elastomer is the reaction product ofdiethylene glycol, adipic acid and toluene diisocyanate (Helastic 1360The impregnated web is next passed into a water bath so as to depositthe elastomer in the composite web. The water bath is equipped withrollers to move the product along. The product is washed with water bypassing it through a second water bath similarly equipped with rollersand finally dried.

The dried substrate thus produced is immersed in a mixture of 70 partsdimethyl formamide and 30 parts water. The wetted product is squeezedthrough rollers to produce a substrate with about 60 percent liquid addon, but no surface film of liquid. The microporous, microcrystalline,resilient, cellulosic, particle-containing elastomeric solutiondescribed in example 4 is then coated onto the surface to produce a wetfilm approximately 2-mils thick. The coated substrate is then passedthrough an aqueous bath containing 70 parts dimethyl formamide and 30parts water to deposit the elastomer as a microporous surface coatingcontaining the particles and extending into the upper strata of thesubstrate.

The process is repeated using the other particlecontaining elastomericsolution dispersions described in example 4 and also using equivalentcompositions in which talc and other inorganic particles of a particlesize of approximately 100 microns are employed. Additional products areprepared using microcrystalline bovine collegen particles ormicrocrystalline hydrated magnesium silicate particles of a particlesize of about 200 Angstroms.

The products by these processes are useful as replacements for naturalleather.

EXAMPLE 6 The products produced by the procedures of example 5 aretreated to increase the degree by which the grain layer extends abovethe surface of the substrate. This is accomplished by first wetting thesubstrate with the same 70:30 dimethyl formamide-water mixture used inexample 5. The wetted substrate is then squeezed to produce a wettedproduct which does not have a surface film of liquid and the thustreated product is spray coated with a solution containing 10 percent byweight of the same polyester polyurethane elastomer used in example 5 indimethyl formamide. The spray-coated product is then passed through awater bath to deposit the elastomer. The products are not laminar. Theelastomer from each successive treatment becomes integrated with theelastomer of the previous treatment so that in the final product thegrain layer extends into the upper strata of the substrate and above itssurface.

The products thus produced are useful as replacements for naturalleather.

EXAMPLE 7 The procedures of example 5 are repeated except that the topfleece in the composite web contains only nylon and no thermoplasticcomponent. Additionally, the composite substrate produced by depositionof the polyurethane elastomer within the composite web is subjected to aheat treatment at 300 F. at a pressure of 80 lbs/sq. inch for 3 minutesbefore the particle-containing grain layers are applied.

The products thus produced are useful as replacements for naturalleather.

EXAMPLE 8 Fibers of 100 percent 1.5 denier by 1.5-inch nylon 66 areair-laid to produce a fleece of 8.5 oz./sq. yard. This fleece isintegrated as described in example 5 into a 0.025-inch-thick sheet ofpolyether polyurethane foam having a density of 1.5 lb./cubic foot. Theresulting web is compressed in a flat press during a dwell time of 3minutes at a pressure of 300 lbs/sq. inch and a temperature of 300 F.The compressed web is the impregnated with a solution of the samepolyester polyurethane elastomer described in example 4 in dimethylformamide with a solids content of 35 percent. The elastomer isdeposited in the web using the same procedures as in example 2. Theproduct is washed, dried and heat treated in a flat press at 275 F. and75 lbs/sq. inch pressure for 3 minutes. The dried substrate is immersedin a water bath and squeezed to remove sufficient water so that there isno surface film. It is coated with a solution containing 25 percent byweight of the same polyester polyurethane elastomer described in thepreparation of the films reported in table 1 and containingapproximately 70 parts of the molecular sieves used in example 4, per100 parts of resin. The product is passed into a water bath to depositthe particle-containing elastomer as a grain layer. lt is then washedwith water and dried.

The procedure is repeated except that no elastomeric filler is depositedin the fiber-foam web and the heat treatment is omitted.

Similar products are produced by repeating the procedure of this exampleexcept that the elastomer is deposited as a .grain layer containingmolecular sieve particles by exposing the elastomer coated substrate toa humid atmosphere in ;which the relative humidity is about 90 percentat room temperature.

The products thus produced are useful as replacements for naturalleather.

EXAMPLE 9 i A polyurethane elastomer is prepared from;polytetramethylene glycol, toluene-2,4-diisocyanate chain extended withethylene diarnine. A 20 percent solution of this elastomer forms astable microporous film having a moisture vapor transmission of about 75mg./cm. /24 hours. The procedure of example 5 is repeated, except thatthe grain layer is formed from the elastomeric solution of this example.The resulting product is useful as a leather replacement.

What is claimed is:

1. A supple, microporous, breathable elastomeric film characterized by asystem of intercommunicating cells communicating with each other andwith the surface of the film, said film being from about 3 to 20 milsthick, and having dispersed therein from about 30 to 120 parts by weightof inert particles per parts by weight of dry elastomer in the sizerange of from about 0.02 microns to 150 microns.

2. A film as in claim 1 wherein the elastomer is selected from the groupconsisting of polyurethane elastomers and mixtures thereof withpolyvinyl chloride elastomers.

3. A film as in claim 1 which is from 5 to 15 mils thick and containsfrom 50 to 80 parts by weight of inert particles in the size range offrom 20 to 70 microns.

4. A film as in claim 1 wherein the particles are.

microporous, microcrystalline resilient cellulosic particles.

5. A film as in claim 1 laminated to a flexible base.

6. A breathable, supple fibrous sheet composition comprising a vaporpermeable substrate containing randomly oriented fibers entangled andinterlocked with each other, and a grain layer comprising a microporouselastomeric composition containing intercommunicating cells, saidelastomeric composition extending above the surface of said substrateand into the upper strata thereof, the said grain layer containing fromabout 30 to parts by weight of inert particles per 100 parts by weightof dry elastomer in the size range of from. about 0.02 microns toMlCRONS.

7. A sheet as in claim 6 wherein the elastomer is selected from thegroup consisting of polyurethane elastomers and mixtures thereof withpolyvinyl chloride elastomers.

8. A sheet as in claim 6 containing from 50 to 80 parts by weight ofinert particles in the size range from 20 to 70 microns.

9. A sheet as in claim 6 in which the particles are microporous,microcrystalline, resilient cellulosic particles.

10. A sheet as in claim 6 wherein the substrate is a web of randomlyoriented fibers entangled and interlocked with each other in apolyurethane foam there being from about 10 percent to 80 percent fibersand from about percent to 90 percent foam in said web based on its totalweight, and having void spaces between said foam and said fibers.

11. A sheet as in claim 6 wherein the substrate is a web of randomlyoriented fibers entangled and interlocked with each other in apolyurethane foam, there being void spaces between said foam and saidfibers, said web having dispersed therein a soft, resilient elastomersubstantially, but not completely, filling said void spaces, the dryelastomer content of said substrate being from about to 75 percent, thefiber content being from about 5 to 55 percent, and the foam contentbeing from about 10 to 60 percent, all based on the total weight of thesubstrate.

12. A sheet as in claim 6 wherein the substrate is a fibrous sheetcharacterized by a gradient density decreasing from the top to thebottom thereof and comprising:

a. a base web which is an interlocking network of randomly oriented anddistributed fibers in a polyurethane foam with void spaces therebetween,

. atop fleece mechanically bonded to the surface of said base web andcomprising additional fibers, the denier of which is no greater than thedenier of said randomly oriented fibers, said additional fibers beingpredominantly in a horizontal plane and having fine intersticestherebetween, and

c. a soft, resilient elastomeric filler which substantially, but

not completely, fills said void spaces and said interstices,

the dry elastomer content of the substrate being from about 25 to 75percent, the fiber content from about 5 to 55 percent and the foamcontent from about l0 to 60 percent, the weight of the top fleece beingfrom about 10 to about 25 percent, all based on the total weight of thesubstrate.

13. A sheet as in claim 12 wherein the top fleece is a fiber blend atleast one member of which is thermoplastic, the weight of thermoplasticfiber being from about 15 to 50 percent based on the total weight offiber in the top fleeces.

2. A film as in claim 1 wherein the elastomer iS selected from the groupconsisting of polyurethane elastomers and mixtures thereof withpolyvinyl chloride elastomers.
 3. A film as in claim 1 which is from 5to 15 mils thick and contains from 50 to 80 parts by weight of inertparticles in the size range of from 20 to 70 microns.
 4. A film as inclaim 1 wherein the particles are microporous, microcrystallineresilient cellulosic particles.
 5. A film as in claim 1 laminated to aflexible base.
 6. A breathable, supple fibrous sheet compositioncomprising a vapor permeable substrate containing randomly orientedfibers entangled and interlocked with each other, and a grain layercomprising a microporous elastomeric composition containingintercommunicating cells, said elastomeric composition extending abovethe surface of said substrate and into the upper strata thereof, thesaid grain layer containing from about 30 to 120 parts by weight ofinert particles per 100 parts by weight of dry elastomer in the sizerange of from about 0.02 microns to 150 MICRONS.
 7. A sheet as in claim6 wherein the elastomer is selected from the group consisting ofpolyurethane elastomers and mixtures thereof with polyvinyl chlorideelastomers.
 8. A sheet as in claim 6 containing from 50 to 80 parts byweight of inert particles in the size range from 20 to 70 microns.
 9. Asheet as in claim 6 in which the particles are microporous,microcrystalline, resilient cellulosic particles.
 10. A sheet as inclaim 6 wherein the substrate is a web of randomly oriented fibersentangled and interlocked with each other in a polyurethane foam therebeing from about 10 percent to 80 percent fibers and from about 20percent to 90 percent foam in said web based on its total weight, andhaving void spaces between said foam and said fibers.
 11. A sheet as inclaim 6 wherein the substrate is a web of randomly oriented fibersentangled and interlocked with each other in a polyurethane foam, therebeing void spaces between said foam and said fibers, said web havingdispersed therein a soft, resilient elastomer substantially, but notcompletely, filling said void spaces, the dry elastomer content of saidsubstrate being from about 25 to 75 percent, the fiber content beingfrom about 5 to 55 percent, and the foam content being from about 10 to60 percent, all based on the total weight of the substrate.
 12. A sheetas in claim 6 wherein the substrate is a fibrous sheet characterized bya gradient density decreasing from the top to the bottom thereof andcomprising: a. a base web which is an interlocking network of randomlyoriented and distributed fibers in a polyurethane foam with void spacestherebetween, b. a top fleece mechanically bonded to the surface of saidbase web and comprising additional fibers, the denier of which is nogreater than the denier of said randomly oriented fibers, saidadditional fibers being predominantly in a horizontal plane and havingfine interstices therebetween, and c. a soft, resilient elastomericfiller which substantially, but not completely, fills said void spacesand said interstices, the dry elastomer content of the substrate beingfrom about 25 to 75 percent, the fiber content from about 5 to 55percent and the foam content from about 10 to 60 percent, the weight ofthe top fleece being from about 10 to about 25 percent, all based on thetotal weight of the substrate.
 13. A sheet as in claim 12 wherein thetop fleece is a fiber blend at least one member of which isthermoplastic, the weight of thermoplastic fiber being from about 15 to50 percent based on the total weight of fiber in the top fleeces.